Every method can be used for sensitive skin, each with its
   pluses and minuses. Let me see if I can recall what worked and
   failed from when I still shaved... Ok: Pre-shave stuff works
   well. There's a limited amount of smells and I don't know what
   his triggers might be, but they're worth trying to what his
   preference is for smells, if any. They're all basically modified
   rubbing alcohol with glycerin in it I think.

   There's also warm washcloth, almost completely dry. It can be as
   hot as he likes - the hotter the better, or after a shower. My
   skin is sensitive so I actually hate showers, both as a kid and
   even now. I tend to use foot powder for body and hair much of
   the time; whatever gets the oils and smells off works but I'm
   always clean. Razor-wise:
   a) for manual razors, the more blades they are, the easier they
   are on sensitive skin. I always used the kind with moisturizing
   strip.

   However: they don't cut quite as closely as fewer blades. But
   there's less burn. Still runs the risk of cutting yourself of
   course.

   I found best success with a cheap 2 blade with moisturizing
   strip. Runs more risk of cut and burn than more blades, but it
   ALSO cut very close. So I learned to be careful.

   Technique is making the skin as taut as possible to allow hairs
   to stick up as much as possible. They always said, "shave with
   the growth". I always shaved against the growth. I liked getting
   REALLY close shaven when I shaved.

   You don't need much shaving cream. I preferred white over the
   gel. I never liked gel anything; either underarm or face. But
   the white stuff was fine. Put it on, let it sit on the face for
   a minutes or two to "sink in", and start.

   b) for electric, there's the foil type (classic electric razor)
   and rotary.

   Every brand is different, every face is different. I went
   through a bunch. Things that claim sensitive skin are somewhat
   mythological; I'd get skin burn from any of them, sensitive or
   not.

   With electric, softer hairs are most important. pre-shave stuff
   and/or shower beforehand.

   Mistakes: pushing on the skin too hard with the electric.

   If you like to get baby ass smooth when you shave, which I did,
   the urge to really dig in there with the electric is STRONG.
   Rubbing in circles for too long. Going back and forth, back and
   forth, back and forth, or pushing REALLY HARD with it into the
   skin to make it work THE FIRST TIME.. .is _so so tempting.

   It leaves you with razor burn, which is hot and itchy and takes
   a couple of days to go away completely for me. Not the end of
   the world, but it's really annoying and looks a little like a
   skin disorder.

   Hm, that's my brain dump for now. If he wants to be REALLY
   SMOOTH and has sensitive skin, expect a lot of trial and error.

   That was always my problem and why a beard (using a hair trimmer
   to curtail growth) was my answer. I'm very lucky I have a nice
   natural beard.

   If he wants to go back to before he was growing hair, expect a
   lot of experimentation, mistakes, rushing, pushing hard. It
   takes a lot of practice.

   He'll have some rough patches too. For me, it's under my neck
   where the adam's apple is. I wanted that to be super smooth and
   by the time I GOT IT that smooth, it was red and hot and
   painful.

   I just quietly suffered with the pain because I wanted to
   achieve the impossible, going back in time.

   Oh, added tip, based on BG observation:

   There is a FLEXIBLE manual razor.

   _THAT_ is excellent. It's the best choice, in my opinion, out of
   the manuals.